U.S. patent number 10,665,742 [Application Number 15/323,517] was granted by the patent office on 2020-05-26 for co-extruded backsheet for solar cell modules.
This patent grant is currently assigned to DSM IP ASSETS B.V.. The grantee listed for this patent is DSM IP Assets B.V.. Invention is credited to Guido Jozefina Wilhelmus Meijers, Franciscus Gerardus Henricus Van Duijnhoven.
United States Patent |
10,665,742 |
Van Duijnhoven , et
al. |
May 26, 2020 |
Co-extruded backsheet for solar cell modules
Abstract
This invention relates to a solar-cell module backing layer
obtained by co-extruding obtained by melt co-extruding (i) a first
polymer composition comprising (a) a polyamide, (b) an elastomer
and (c) an elastomer that contains groups that bond chemically
and/or interact physically with the polyamide, and wherein the
first polymer composition comprises from 10 to 90 wt. % of the
polyamide (a) and from 10 to 90 wt. % of the elastomer (b) and (c)
(of the total weight of polyamide (a) and elastomer (b) and (c)
present in the first polymer composition) and (ii) a second polymer
composition comprising from 50-98 wt. % of elastomer and from
0.15-5 wt. % of groups (based on the total weight of the second
polymer composition) that bond chemically and/or interact
physically with the solar cell and optionally with the first
polymer composition.
Inventors: |
Van Duijnhoven; Franciscus Gerardus
Henricus (Echt, NL), Meijers; Guido Jozefina
Wilhelmus (Echt, NL) |
Applicant: |
Name |
City |
State |
Country |
Type |
DSM IP Assets B.V. |
Heerlen |
N/A |
NL |
|
|
Assignee: |
DSM IP ASSETS B.V. (Heerlen,
NL)
|
Family
ID: |
51059362 |
Appl.
No.: |
15/323,517 |
Filed: |
July 1, 2015 |
PCT
Filed: |
July 01, 2015 |
PCT No.: |
PCT/EP2015/064938 |
371(c)(1),(2),(4) Date: |
January 03, 2017 |
PCT
Pub. No.: |
WO2016/001280 |
PCT
Pub. Date: |
January 07, 2016 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20170148940 A1 |
May 25, 2017 |
|
Foreign Application Priority Data
|
|
|
|
|
Jul 4, 2014 [EP] |
|
|
14175785 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08J
5/18 (20130101); H01L 31/049 (20141201); C08L
51/06 (20130101); C08J 2351/06 (20130101); C08J
2423/08 (20130101); Y02E 10/50 (20130101); C08J
2477/06 (20130101); C08J 2433/14 (20130101) |
Current International
Class: |
H01L
31/049 (20140101); C08L 51/06 (20060101); C08J
5/18 (20060101) |
References Cited
[Referenced By]
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Other References
International Search Report for PCT/EP2015/064938 dated Sep. 23,
2015, 2 pages. cited by applicant .
Written Opinion of the ISA for PCT/EP2015/064938 dated Sep. 23,
2015, 4 pages. cited by applicant .
D.J. Shanefield, Organic Additives and Ceramic Processing,,
Springer Science+Business Media New York, 1195, compares van der
Waals bonding as a type of physical bond with ionic, covalent and
coordinate covalent types of chemical bonds, Fig 2.1, p. 9. cited
by applicant .
J.L. Hopton, Knockhardy Notes--A level Chemistry, 1997, is a high
school reference page which provides a concise summary of the types
of physical bonds that exist; and notes their difference to
chemical bonds. cited by applicant.
|
Primary Examiner: Woodward; Ana L.
Attorney, Agent or Firm: Bull; Kevin M.
Claims
The invention claimed is:
1. A solar-cell module backing layer obtained by melt co-extruding
(i) a first polymer composition comprising (a) a polyamide, (b) a
non-functionalized elastomer and (c) a functionalized elastomer
that contains groups that bond chemically and/or physically with
the polyamide, and wherein the first polymer composition comprises
from 10 to 90 wt. % of the polyamide (a) and from 10 to 90 wt. % of
the non-functionalized elastomer (b) and the functionalized
elastomer (c) (of the total weight of polyamide (a),
non-functionalized elastomer (b) and functionalized elastomer (c)
present in the first polymer composition) and (ii) a second polymer
composition comprising from 50 to 98 wt. % of an elastomer and from
0.15-5 wt. % of groups (based on the total weight of the second
polymer composition) that bond chemically and/or physically with a
solar cell and optionally with the first polymer composition.
2. The backing layer according to claim 1, wherein the polyamide
(a) constitutes the continuous phase of the first polymer
composition and the non-functionalized elastomer (b) and
functionalized elastomer (c) constitute the dispersed phase of the
first polymer composition and wherein the first polymer composition
comprises from 50 to 90 wt. % of the polyamide (a) and from 10 to
50 wt. % of the non-functionalized elastomer (b) and the
functionalized elastomer (c) (of the total weight of polyamide (a)
non-functionalized elastomer (b) and functionalized elastomer (c)
present in the first polymer composition).
3. The backing layer according to claim 1, wherein the amount, in
the first polymer composition, of functionalized elastomer (c) that
contains groups that bond chemically and/or physically with the
polyamide is from 5 to 50 wt. % (of the total weight of
non-functionalized elastomer (b) and functionalized elastomer (c)
in the first polymer composition).
4. The backing layer according claim 1, wherein the polyamide is
selected from the group consisting of polyamide-6,6, polyamide-4,6,
polyamide-6, and any mixture thereof.
5. The backing layer according to claim 1, wherein the
non-functionalized elastomer (b) in the first polymer composition
is a copolymer of ethylene and C3-C12-.alpha.-olefin with a density
of from 0.85 to 0.93 g/cm.sup.3 and a Melt Flow Index (ASTM D1238,
190.degree. C., 2.16 kg) of from 0.5 to 30 g/10 min.
6. The backing layer according to claim 5, wherein the copolymer of
ethylene and C3-C12-.alpha.-olefin is an ethylene-octene
copolymer.
7. The backing layer according to claim 6, wherein the
ethylene-octene copolymer is obtained by polymerization in the
presence of a metallocene catalyst.
8. The backing layer according claim 1, wherein the functionalized
elastomer (c) comprises groups that bond chemically with the
polyamide.
9. The backing layer according to claim 8, wherein the groups that
bond chemically with the polyamide are chosen from the group
consisting of anhydrides, acids, epoxides, silanes, isocyanates,
oxazolines, thiols and/or (meth)acrylates.
10. The backing layer according to claim 8, wherein the groups that
bond chemically with the polyamide are chosen from the group
consisting of unsaturated dicarboxylic acid anhydrides, unsaturated
dicarboxylic acids, unsaturated dicarboxylic acid esters, and
mixtures of two or more thereof.
11. The backing layer according to claim 8, wherein the
functionalized elastomer (c) is obtained by graft polymerizing
elastomer with maleic acid, maleic anhydride and/or fumaric
acid.
12. The backing layer according claim 1, wherein the groups present
in the second polymer composition that bond chemically and/or
physically with a solar cell are chosen from the group consisting
of anhydrides, acids, epoxides, silanes, isocyanates, oxazolines,
thiols, (meth)acrylates, and mixtures thereof.
13. The backing layer according to claim 1, wherein the groups
present in the second polymer composition that bond chemically
and/or physically with a solar cell are chosen from the group
consisting of silanes, epoxides, anhydrides, a combination of
silanes and epoxides, or a combination of anhydrides and
epoxides.
14. The backing layer according to claim 1, wherein silane groups
and epoxide groups are present in the second polymer
composition.
15. The backing layer according to claim 1, wherein the groups that
bond chemically and/or physically with a solar cell are introduced
in the second polymer composition by blending an elastomer that
contains such groups into the second polymer composition.
16. The backing layer according to claim 1, wherein the amount of
groups present in the second polymer composition that bond
chemically and/or interact physically with a solar cell is from
0.025 to 2 wt. % (of the total weight of the second polymer
composition).
17. The backing layer according to claim 1, wherein the elastomer
in the second polymer composition is a copolymer of ethylene and
C3-C12-.alpha.-olefin with a density of from 0.85 to 0.93
g/cm.sup.3 and a Melt Flow Index (ASTM D1238, 190.degree. C., 2.16
kg) of from 0.5 to 30 g/10 min.
18. The backing layer according to claim 17, wherein the copolymer
of ethylene and C3-C12-.alpha.-olefin is an ethylene-octene
copolymer.
19. A solar-cell module comprising, in order of position from the
front sun-facing side to the back non-sun-facing side, a
transparent pane, a front encapsulant layer, a solar cell layer
comprised of one or more electrically interconnected solar cells,
and a backing layer, wherein the backing layer is connected to the
lower sides of the solar cells, wherein the backing layer is
according to claim 1 and is positioned in such a way that the first
polymer composition is at the back non-sun-facing side of the
module.
20. The solar-cell module according to claim 19, wherein the solar
cells in the solar cell layer are wafer-based solar cells.
Description
This application is the U.S. national phase of International
Application No. PCT/EP2015/064938 filed Jul. 1, 2015 which
designated the U.S. and claims priority to EP Patent Application
No. 14175785.6 filed Jul. 4, 2014, the entire contents of each of
which are hereby incorporated by reference.
The present invention is directed to back sheets for solar cell
modules. The present invention also relates to solar cell modules
comprising such a back sheet. Further, the present invention
relates to a polymer composition that can be used to produce back
sheets for solar cell modules.
Solar cell or photovoltaic modules are used to generate electrical
energy from sunlight and consist of a laminate which contains a
solar cell system as the core layer. This core layer (herein also
referred to as solar cell layer) is encapsulated with encapsulating
materials which serve as protection against mechanical and
weathering-induced influences. These encapsulating materials can
consist of one or more layers of plastic films and/or plastic
composites.
Because they provide a sustainable energy resource, the use of
solar cells is rapidly expanding. The more traditional solar cells
are the wafer-based solar cells.
Monocrystalline silicon (c-Si), poly- or multi-crystalline silicon
(poly-Si or mc-Si) and ribbon silicon are the materials used most
commonly in forming the more traditional wafer-based solar cells.
Solar cell modules derived from wafer-based solar cells often
comprise a series of self-supporting wafers (or cells) that are
soldered together. The wafers generally have a thickness of between
about 180 and about 240 micron. Such a panel of solar cells is
called a solar cell layer and it may further comprise electrical
wirings such as cross ribbons connecting the individual cell units
and bus bars having one end connected to the cells and the other
exiting the module. The solar cell layer is then further laminated
to encapsulant layer(s) and protective layer(s) to form a weather
resistant module that may be used for at least 20 years. In
general, a solar cell module derived from wafer-based solar cell(s)
comprises, in order of position from the front sun-facing side to
the back non-sun-facing side: (1) a transparent pane (representing
the front sheet), (2) a front encapsulant layer, (3) a solar cell
layer, (4) a back encapsulant layer, and (5) a backing layer (or
back sheet, representing the rear protective layer of the
module).
The encapsulant layers used in solar cell modules are designed to
encapsulate and protect the fragile solar cells. Suitable polymer
materials for solar cell encapsulant layers typically possess a
combination of characteristics such as high impact resistance, high
penetration resistance, good ultraviolet (UV) light resistance,
good long term thermal stability, adequate adhesion strength to
glass and/or other rigid polymeric sheets, high moisture
resistance, and good long term weatherability. Currently,
ethylene/vinyl acetate copolymers are the most widely used
encapsulant material and polyvinylfluoride and polyethylene
terephthalate are the most widely used materials for back sheets in
the industry.
When solar cell modules are used in the field, it is found that if
the encapsulant sheet and the back sheet are not tightly sealed,
moisture tends to enter and cause de-lamination and/or breakdown
voltage. There is thus still a need to develop an encapsulant and
backsheet material having superior adhesion to each other and
therefore improve the weatherability of the solar cell module.
In contrast to the prior art, which typically provides multilayered
backsheets and adhered thereto a back encapsulant layer, the object
of the present invention is to identify suitable materials that can
be used for producing a layer for a solar-cell module to be used as
backing layer which backing layer is connected to the lower sides
of the solar cells. In the present invention, the backing layer
integrates the function of the back encapsulant layer and the back
sheet in one layer and is to be used as rear layer for a solar-cell
module.
This object has been achieved in that the backing layer is obtained
or obtainable by melt co-extruding (i) a first polymer composition
comprising (a) a polyamide, (b) an elastomer and (c) an elastomer
that contains groups that bond chemically and/or interact
physically with the polyamide, and wherein the first polymer
composition comprises from 10 to 90 wt. % of the polyamide (a) and
from 10 to 90 wt. % of the elastomer (b) and (c) (based on the
total weight of polyamide (a) and elastomer (b) and (c) present in
the first polymer composition) and (ii) a second polymer
composition comprising from 50 to 98 wt. % (preferably from 60 to
98 wt. %, more preferably from 70 to 98 wt. %, even more preferably
from 80 to 98 wt. %) of elastomer and from 0.15-5 wt. % of groups
(based on the weight of the second polymer composition) that bond
chemically and/or interact physically with the solar cell and
optionally with the first polymer composition. The backing layer is
in a single layer form made by melt co-extruding the first and
second polymer composition.
It has surprisingly been found that the backing layer as claimed is
applicable as rear layer for a solar-cell module and integrates the
function of a back encapsulant layer and a back sheet. The use of
one layer instead of several layers has several advantages such as
no delamination, more simple production of the solar-cell module as
at least one layer less needs to be laminated. Further the risk
that moisture and/or oxygen enters between the rear backing layer
and rear encapsulant layer during the production of the solar cell
module is reduced and hence the risk for delamination and/or
electrical breakdown is reduced.
The elastomer as mentioned herein means a polymeric compound with a
Young's modulus (measured at 23.degree. C. according to ISO 527 1A)
of from 2 MPa to 400 MPa. Preferably from 5 to 300 MPa, more
preferably from 5 to 200 MPa and even more preferably from 5 to 100
MPa.
Preferably, the polyamide (a) constitutes the continuous phase of
the first polymer composition and the elastomers (b) and (c)
constitutes the dispersed phase of the first polymer composition
and the first polymer composition comprises from 50 to 90 wt. % of
the polyamide (a) and from 10 to 50 wt. % of the elastomer (b) and
(c) (of the total weight of polyamide (a) and elastomer (b) and (c)
present in the first polymer composition). This results in improved
dimensional stability (as shown for example by less shrinkage)
during the lamination process for preparing the solar cell.
The amount of groups present in the first polymer composition that
bond chemically and/or interact physically with the polyamide is
preferably from 0.01 to 5 wt. %. The best results are generally
achieved with a content of 0.025 to 2 wt. %, preferably from 0.05
to 2 wt. % (based on the total weight of the first polymer
composition). The weight ratio of non-functionalized to
functionalized elastomer in the first polymer composition may vary
within wide limits and is determined in part by the functional
groups content of the elastomer and the available reactive groups
in the polyamide polymer. Preferably, the amount, in the first
polymer composition, of elastomer (c) that contains groups that
bond chemically and/or interact physically with the polyamide
(functionalized elastomer) is from 5 to 50 wt. % (of the total
amount of elastomer (b) and (c) in the first polymer
composition).
The polyamide present in the first polymer composition is
preferably selected from the group consisting of polyamide-6,6,
polyamide-4,6 and polyamide-6 and any mixture thereof; more
preferably the polyamide is polyamide-6.
The elastomer (b) of the first polymer composition is preferably a
copolymer of ethylene and C3-C12-.alpha.-olefin with a density of
from 0.85 to 0.93 g/cm.sup.3 and a Melt Flow Index (ASTM D1238,
190.degree. C., 2.16 kg) of from 0.5 to 30 g/10 min. More
preferably, the elastomer (b) of the first polymer composition is
an ethylene-octene copolymer with a density of from 0.85 to 0.93
g/cm.sup.3 and a Melt Flow Index (ASTM D1238, 190.degree. C., 2.16
kg) of from 0.5 to 30 g/10 min. Even more preferably, said
ethylene-octene copolymer is obtained by polymerization in the
presence of a metallocene catalyst since it was found that this
results in improved compatibility of the polyamide and the
elastomer in the first polymer composition.
The elastomer (c) of the first polymer composition is preferably a
copolymer of ethylene and C3-C12-.alpha.-olefin with a density of
from 0.85 to 0.93 g/cm.sup.3 and a Melt Flow Index (ASTM D1238,
190.degree. C., 2.16 kg) of from 0.5 to 30 g/10 min, which
copolymer contains groups that bond chemically and/or interact
physically with the polyamide. Preferably, the copolymer is an
ethylene-octene copolymer with a density of from 0.85 to 0.93
g/cm.sup.3 and a Melt Flow Index (ASTM D1238, 190.degree. C., 2.16
kg) of from 0.5 to 30 g/10 min. Even more preferably, said
ethylene-octene copolymer is obtained by polymerization in the
presence of a metallocene catalyst since this results in improved
compatibility of the polyamide and the elastomer in the first
polymer composition. The non-functionalized elastomer and the
elastomer that is functionalized may be identical or different. An
example of a suitable combination is an ethylene-octene copolymer
and an ethylene-octene copolymer modified with for instance maleic
anhydride.
In the present invention, an elastomer that contains groups that
bond chemically and/or interact physically with the polyamide is
present in the first polymer composition. Preferably, the first
polymer composition comprises functionalized elastomer (c) that
contains groups that bond chemically with the polyamide.
Preferably, the groups that bond chemically with the polyamide are
chosen from the group consisting of anhydrides, acids, epoxides,
silanes, isocyanates, oxazolines, thiols and/or (meth)acrylates,
with the proviso that the combination of silane and anhydride is
preferably excluded, since the presence of silanes in combination
with anhydrides may result in gelation of the polymer composition.
More preferably, the groups that bond chemically with the polyamide
are chosen from the group consisting of unsaturated dicarboxylic
acid anhydrides, unsaturated dicarboxylic acids and unsaturated
dicarboxylic acid esters and mixtures of the two or more thereof.
Even more preferably, the groups that bond chemically with the
polyamide are chosen from the group consisting of unsaturated
dicarboxylic acid anhydrides. Most preferably, the elastomer that
contains groups that bond chemically with the polyamide is obtained
by graft polymerizing the elastomer with maleic acid, maleic
anhydride and/or fumaric acid, preferably with maleic
anhydride.
The groups present in the second polymer composition that bond
chemically and/or interact physically with the solar cell are
preferably chosen from the functional group consisting of
anhydrides, acids, epoxides, silanes, isocyanates, oxazolines,
thiols and/or (meth)acrylates, with the proviso that the
combination of silane and anhydride is preferably excluded, since
the presence of silanes in combination with anhydrides may result
in gelation of the polymer composition. More preferably, the groups
present in the second polymer composition that bond chemically
and/or interact physically with the solar cell are chosen from the
group consisting of silanes, epoxides, anhydrides, combination of
silanes and epoxides or combination of anhydrides and epoxides.
Even more preferably, the groups present in the second polymer
composition that bond chemically and/or interact physically with
the solar cell are chosen from the group consisting of silanes and
epoxides.
In a preferred embodiment, the groups that bond chemically and/or
interact physically with the solar cell are introduced in the
second polymer composition by blending elastomer that contains such
groups into the second polymer composition. This embodiment is
preferred since in case introducing the functional groups in
another way may result in evaporating of the groups from the second
polymer composition.
Preferably, the amount of groups present in the second polymer
composition that bond chemically and/or interact physically with
the solar cell is from 0.025 to 2 wt. %, preferably from 0.05 to 2
wt. % (of the total weight of the second polymer composition).
Preferably, the elastomer in the second polymer composition is a
copolymer of ethylene and C3-C12-.alpha.-olefin with a density of
from 0.85 to 0.93 g/cm.sup.3 and a Melt Flow Index (ASTM D1238,
190.degree. C., 2.16 kg) of from 0.5 to 30 g/10 min. Preferably,
the copolymer is an ethylene-octene copolymer with a density of
from 0.85 to 0.93 g/cm.sup.3 and a Melt Flow Index (ASTM D1238,
190.degree. C., 2.16 kg) of from 0.5 to 30 g/10 min. Even more
preferably, said ethylene-octene copolymer is obtained by
polymerization in the presence of a metallocene catalyst since this
lowers the amount of low Mw species in the ethylene-octene
copolymer that is able to migrate and reduce the adhesion
property.
Preferably, the elastomer present in the first polymer composition
is identical to the elastomer present in the second polymer
composition. An example of a suitable elastomer is an
ethylene-octene copolymer, preferably an ethylene-octene copolymer
as defined hereinabove.
Functional groups can be introduced in the elastomer in many ways.
Preferred ways are by chemical modification of the elastomer or by
graft polymerization of the elastomer with components containing
functional groups as defined hereinabove. Non-limiting and
preferred examples of such components are unsaturated dicarboxylic
acid anhydrides or an unsaturated dicarboxylic acid or an ester
thereof, for instance maleic anhydride, maleic acid, fumaric acid,
itaconic acid and itaconic anhydride; unsaturated epoxide such as
glycidyl acrylate, for example glycidyl methacrylate; and
unsaturated silanes such as for example vinyltrimethoxysilane,
vinyltriethoxysilane, vinyltris(beta-methoxyethoxy)silane,
gamma-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane,
gamma-glycidoxypropyltrimethoxysilane,
gamma-glycidoxypropyltriethoxysilane,
beta-(3,4-epoxycyclohexyl)ethyltrimethoxysilane,
vinyltrichlorosilane or mixtures of two or more thereof.
The first and second polymer composition used herein may further
comprise one or more other polymers. Such optional polymer(s) may
be present in an amount of up to about 25 wt percent, based on the
total weight of the polymer composition, provided that the
inclusion of such optional polymer(s) does not adversely affect the
desirable performance characteristics of the backing layer obtained
by melt co-extruding the first and second polymer composition, such
as the adhesion properties and the integrated function of back
encapsulant layer and back sheet.
The first and second polymer composition may further comprise
additives known within the art. The first and second polymer
composition preferably comprise at least one additive selected from
UV stabilizers, UV absorbers, anti-oxidants, thermal stabilizers
and/or hydrolysis stabilisers. When such additives stabilizers are
used, the polymer composition contains from 0.05 wt. % percent to
10 wt. %, more preferably to 5 wt. %, based on the total weight of
the polymer composition. Through the selection of the polyamide,
the elastomer and the functional groups of the first and second
polymer composition from the described types and amounts, and the
optional addition of one or more of these additives, the layer
obtained by melt co-extruding the first and second polymer
composition fulfills all essential requirements for solar-cell
module backing layer, such as weathering stability (UV and
hydrolysis resistance), heat resistance, mechanical protection,
electrical insulation and good adhesion.
White pigments such as TiO2, ZnO or ZnS may be added to the to one
or both layers to increase backscattering of sunlight leading to
increased efficiency of the PV module. Black pigments such as
carbon black may be added to one or both layers for esthetic
reasons.
The thickness of the solar-cell module backing layer is preferably
from 0.1 to 1 mm, more preferably from 0.1 to 0.8 mm, even more
preferably from 0.1 to 0.75 mm.
The solar-cell module backing layer according to the invention is
obtained by melt co-extruding of the first and second polymer
composition. The process for melt co-extruding of the first and
second polymer composition comprises the following steps: a)
Preparing the first polymer composition by mixing the components,
b) Preparing the second polymer composition by mixing the
components, c) Melting of the first polymer composition to obtain a
first melt stream, d) Melting of the second polymer composition to
obtain a second melt stream, e) Combining the melt streams by
co-extrusion in one extrusion die, f) Cooling the co-extruded
layer.
Preferably steps a)-d) are effected in an extruder. When effecting
steps a)-d) in an extruder, the thickness of the first melt stream
is preferably from 0.05 to 0.8 mm, more preferably from 0.05 to 0.7
mm, even more preferably from 0.05 to 0.5 mm and the thickness of
the second melt stream is preferably from 0.05 to 0.95 mm, more
preferably from 0.05 to 0.75 mm, even more preferably from 0.05 to
0.7 mm.
In a preferred embodiment, the thickness of the solar-cell module
backing layer is from 0.1 to 1 mm, whereby the thickness of the
first melt stream is from 0.05 to 0.8 mm and the thickness of the
second melt stream is from 0.05 to 0.95 mm. In another preferred
embodiment, the thickness of the solar-cell module backing layer is
from 0.1 to 0.8 mm, whereby the thickness of the first melt stream
is from 0.05 to 0.7 mm and the thickness of the second melt stream
is from 0.05 to 0.75 mm. In another preferred embodiment, the
thickness of the solar-cell module backing layer is from 0.1 to
0.75 mm, whereby the thickness of the first melt stream is from
0.05 to 0.5 mm and the thickness of the second melt stream is from
0.05 to 0.7 mm.
The present invention further relates to the use of the co-extruded
sheet as described herein above as backing layer for a solar cell
module, characterized in that the backing layer is the rear layer
of the solar-cell module and the backing layer is connected to the
lower sides of the solar cells.
The present invention further relates to a solar-cell module
containing essentially, in order of position from the front-sun
facing side to the back non-sun-facing side, a transparent pane, a
front encapsulant layer, a solar cell layer comprised of one or
more electrically interconnected solar cells, and a backing layer,
wherein the backing layer is connected to the lower sides of the
solar cells, characterized in that the backing layer is as defined
herein above and is positioned in such a way that the first polymer
composition is at the back non-sun facing side of the module. The
solar cells in the solar cell layer may be any kind of solar cells,
such as thin-film solar cells (for example copper indium gallium
selenide solar cells and cadmium telluride solar cells) and
wafer-based solar cells.
The present invention further relates to a process for preparing
such solar cell module, which process comprises (a) providing an
assembly comprising all the components layers recited above and (b)
laminating the assembly to form the solar cell module. The
laminating step of the process may be conducted by subjecting the
assembly to heat and optionally vacuum or pressure.
The present invention further relates to a polymer composition
comprising (a) a polyamide, (b) an elastomer and (c) an elastomer
that contains groups that bond chemically and/or interact
physically with the polyamide, and wherein the first polymer
composition comprises from 10 to 90 wt. % of the polyamide (a) and
from 10 to 90 wt. % of the elastomer (b) and (c) (of the total
weight of polyamide (a) and elastomer (b) and (c) present in the
first polymer composition). Preferred embodiments for such a
polymer composition are described herein above.
The invention is now demonstrated by means of a series of examples
and comparative experiments.
TABLE-US-00001 TABLE 1 Materials used Description ICOSOLARO .RTM.
AAA 3554 obtained from Laminate of 3 polyamide layers Isovoltaic
ICOSOLAR .RTM. 2442 obtained from Laminate of 3 layers: polyvinyl
fluoride- Isovoltaic polyethylene terephtalate-polyvinyl fluoride
APOLHYA .RTM. Solar R333A obtained from Polyolefin back
encapsulant- Arkema polyethylene with grafted polyamide EVASKY .TM.
from Bridgestone Ethylene-vinyl acetate copolymer Akulon .RTM. K122
from DSM Polyamide-6 Cupper Iodide powder obtained from Thermal
stabilizer BASF Irganox .RTM. 1098 obtained from BASF Anti-oxidant
Queo .TM. 1007 obtained from Borealis LLDPE (ethylene based octene
Plastomers elastomer) with density of 910 g/cm.sup.3 and MFI of 7
Queo .TM. 8201 obtained from Borealis LLDPE (ethylene based octene
Plastomers elastomer) with density of 882 g/cm.sup.3 and MFI of 1
Methacryloxy propyl trimethoxy silane obtained from BRB Lotader
.RTM. AX8840 obtained from Arkema Random copolymer of ethylene and
glycidyl methacrylate (epoxy functional elastomer) Fusabond .RTM. N
525 obtained from DuPont Anhydride modified ethylene copolymer
(elastomer) Glass plate from Centro Solar SECURIT EN12150
COMPARATIVE EXPERIMENT A
This example is a reference and only commercial encapsulant and
backsheet films were used.
A laminate was made by making the following stack: 1) ICOSOLAR.RTM.
AAA 3554, 2) APOLHYA.RTM. Solar R333A, 3) one standard
multi-crystalline solar cell, 4) APOLHYA.RTM. Solar R333A, 5) glass
plate of 20 by 30 cm. Lamination was done at 157.degree. C. during
12 minutes.
Samples were aged in a climate chamber at 85.degree. C. and 85%
relative humidity. Samples were exposed to a damp heat test.
It was visually assessed that the sample showed no delamination
during 3000 hours of ageing. It was assessed after 3000 hours of
ageing, by hand, that the layer of ICOSOLAR.RTM. AAA 3554 became
brittle between 2000 and 3000 hours of ageing. Flash testing did
not show any significant decrease of the power output after 2000
hours of ageing.
COMPARATIVE EXPERIMENT B
This example is a reference and only commercial encapsulant and
backsheet films were used.
A laminate was made by making the following stack: 1) ICOSOLAR.RTM.
AAA 3554, 2) EVASKY.TM., 3) one standard multi-crystalline solar
cell, 4) EVASKY.TM.5) glass plate of 20 by 30 cm. Lamination was
done at 157.degree. C. during 12 minutes.
Samples were aged in a climate chamber at 85.degree. C. and 85%
relative humidity. Samples were exposed to a damp heat test.
It was visually assessed that the sample showed no delamination
during 3000 hours of ageing. It was assessed after 3000 hours of
ageing, by hand, that the layer of ICOSOLAR.RTM. AAA 3554 became
brittle between 2000 and 3000 hours of ageing. Flash testing did
not show any significant decrease of the power output after 2000
hours of ageing.
COMPARATIVE EXPERIMENT C
This example is a reference and only commercial encapsulant and
backsheet films were used.
A laminate was made by making the following stack: 1) ICOSOLAR.RTM.
2442, 2) EVASKY.TM., 3) one standard multi-crystalline solar cell,
4) EVASKY.TM., 5) glass plate of 20 by 30 cm. Lamination was done
at 157.degree. C. during 12 minutes.
Samples were aged in a climate chamber at 85.degree. C. and 85%
relative humidity.
It was visually assessed that the sample showed no delamination
during 3000 hours of ageing. It was assessed after 3000 hours of
ageing, by hand, that the layer of ICOSOLAR.RTM. 2442 became very
brittle between 2000 and 3000 hours of ageing. Flash testing did
not show any significant decrease of the power output after 2000
hours of ageing.
COMPARATIVE EXPERIMENT D
This example is a reference experiment for which no adjustments
have been done to the bottom "backsheet" layer. Two different
compounds were made on a ZSK25 extruder. The first compound
contained 96.85 wt % Akulon.RTM. K122, 0.15 wt % Cupper Iodide, and
3 wt % Irganox.RTM. 1098. The second compound contained 65 wt %
Queo.TM. 1007, 25 wt % Queo.TM. 1007 to which 2 wt % methacryloxy
propyl trimethoxy silane (BRB) is grafted and 10 wt % Lotader.RTM.
AX8840. From the first compound a 200 micrometer film was made via
film-extrusion. From the second compound a 500 micrometer film was
made via film-extrusion.
A laminate was made by making the following stack: 1) film of
compound 1 2) film of compound 2 3) one standard multi-crystalline
solar cell 4) APOLHYA.RTM. Solar R333A 5) glass plate of 20 by 30
cm. Lamination was done at 157.degree. C. during 12 minutes.
Samples were aged in a climate chamber at 85.degree. C. and 85%
relative humidity.
It was visually assessed that the sample showed clear delamination
at the side of the glass, which became significant during 3000
hours of ageing. Consequently, the IEC norm. was not met.
EXAMPLE 1
Two different compounds were made on a ZSK25 extruder. The first
compound contained 50 wt % Akulon.RTM. K122, 34.85 wt % Queo.TM.
8201, 10 wt % Fusabond N525, 0.15 wt % Cupper Iodide, and 3 wt %
Irganox.RTM. 1098. The second compound contained 65 wt % Queo.TM.
1007, 25 wt % Queo.TM. 1007 to which 2 wt % methacryloxy propyl
trimethoxy silane (BRB) is grafted and 10 wt % Lotader.RTM. AX8840
(Arkema). A film was made by co-extrusion a 200 micrometer film of
compound 1 with a 500 micrometer film of compound 2. The extrusion
die was set at a temperature of 250.degree. C.
A laminate was made by making the following stack: 1) above
co-extruded film, 2) one standard multi-crystalline solar cell, 3)
APOLHYA.RTM. Solar R333A, 4) glass plate of 20 by 30 cm. Lamination
was done at 157.degree. C. during 12 minutes.
Samples were aged in a climate chamber at 85.degree. C. and 85%
relative humidity.
It was visually assessed that the sample showed no delamination
during 3000 hours of ageing. Flash testing did not show any
significant decrease of the power output after 3000 hours of
ageing.
EXAMPLE 2
The same compounds as produced in example 1 were co-extruded into a
film having a total thickness of 600 micrometers and consisting of
a 400 micrometer layer of the first compound and a 200 micrometer
layer of the second compound. The extrusion die was set at a
temperature of 270.degree. C.
A laminate was made by making the following stack: 1) above
co-extruded film, 2) one standard multi-crystalline solar cell, 3)
APOLHYA.RTM. Solar R333A, 4) glass plate of 20 by 30 cm. Lamination
was done at 157.degree. C. during 12 minutes.
Samples were aged in a climate chamber at 85.degree. C. and 85%
relative humidity.
It was visually assessed that the sample showed no delamination
during 3000 hours of ageing. Flash testing did not show any
significant decrease of the power output after 3000 hours of
ageing.
EXAMPLE 3
Two different compounds were made on a ZSK25 extruder. The first
compound contained 50 wt % Akulon.RTM. K122, 34.85 wt % Queo.TM.
8201, 10 wt % Fusabond.RTM. N 525, 0.15 wt % Cupper Iodide, and 3
wt % Irganox.RTM. 1098. The second compound contained 90 wt %
Queo.TM. 1007 and 10 wt % Lotader.RTM. AX8840. A film was made by
co-extrusion a 200 micrometer film of compound 1 with a 500
micrometer film of compound 2. The extrusion die was set at a
temperature of 250.degree. C.
A laminate was made by making the following stack: 1) above
co-extruded film, 2) one standard multi-crystalline solar cell 3)
APOLHYA.RTM. Solar R333A 4) glass plate of 20 by 30 cm. Lamination
was done at 157.degree. C. during 12 minutes.
Samples were aged in a climate chamber at 85.degree. C. and 85%
relative humidity.
It was visually assessed that the sample showed no delamination
during 3000 hours of ageing. Flash testing did not show any
significant decrease of the power output after 3000 hours of
ageing.
EXAMPLE 4
The same compounds as produced in example 3 were co-extruded into a
film having a total thickness of 600 micrometers and consisting of
a 400 micrometer layer of the first compound and a 200 micrometer
layer of the second compound. The extrusion die was set at a
temperature of 270.degree. C.
A laminate was made by making the following stack: 1) above
co-extruded film, 2) one standard multi-crystalline solar cell 3)
APOLHYA.RTM. Solar R333A 4) glass plate of 20 by 30 cm. Lamination
was done at 157.degree. C. during 12 minutes. Samples were aged in
a climate chamber at 85.degree. C. and 85% relative humidity.
It was visually assessed that the sample showed no delamination
during 3000 hours of ageing. Flash testing did not show any
significant decrease of the power output after 3000 hours of
ageing.
EXAMPLE 5
Two different compounds were made on a ZSK25 extruder. The first
compound contained 50 wt % Akulon.RTM. K122, 40 wt % Queo.TM. 8201,
10 wt % Fusabond.RTM. N 525. The second compound contained 65 wt %
Queo.TM. 1007, 25 wt % Queo.TM. 1007 to which 2 wt % methacryloxy
propyl trimethoxy silane (BRB) is grafted and 10 wt % Lotader.RTM.
AX8840 (Arkema). A film was made by co-extrusion a 200 micrometer
film of compound 1 with a 500 micrometer film of compound 2. The
extrusion die was set at a temperature of 250.degree. C.
A laminate was made by making the following stack: 1) above
co-extruded film, 2) one standard multi-crystalline solar cell 3)
APOLHYA.RTM. Solar R333A 4) glass plate of 20 by 30 cm. Lamination
was done at 157.degree. C. during 12 minutes.
Samples were aged in a climate chamber at 85.degree. C. and 85%
relative humidity.
It was visually assessed that the sample showed no delamination
during 3000 hours of ageing. Flash testing did not show any
significant decrease of the power output after 3000 hours of
ageing.
EXAMPLE 6
The same compounds as produced in example 5 were co-extruded into
film having a total thickness of 600 micrometers and consisting of
a 400 micrometer layer of the first compound and a 200 micrometer
layer of the second compound. The extrusion die was set at a
temperature of 270.degree. C.
A laminate was made by making the following stack: 1) above
co-extruded film, 2) one standard multi-crystalline solar cell 3)
APOLHYA.RTM. Solar R333A 4) glass plate of 20 by 30 cm. Lamination
was done at 157.degree. C. during 12 minutes.
Samples were aged in a climate chamber at 85.degree. C. and 85%
relative humidity.
It was visually assessed that the sample showed no delamination
during 3000 hours of ageing. Flash testing did not show any
significant decrease of the power output after 3000 hours of
ageing.
EXAMPLE 7
Two different compounds were made on a ZSK25 extruder. The first
compound contained 50 wt % Akulon.RTM. K122, 34.85 wt % Queo.TM.
8201, 10 wt % Fusabond.RTM. N 525, 0.15 wt % Cupper Iodide, and 3
wt % Irganox.RTM. 1098. The second compound contained 67.5 wt %
Queo.TM. 1007, 22.5 wt % Queo.TM. 1007 to which 2 wt % methacryloxy
propyl trimethoxy silane (BRB) is grafted and 10 wt % Fusabond.RTM.
N 525. A film was made by co-extrusion a 200 micrometer film of
compound 1 with a 500 micrometer film of compound 2. The extrusion
die was set at a temperature of 250.degree. C.
A laminate was made by making the following stack: 1) above
co-extruded film, 2) one standard multi-crystalline solar cell 3)
APOLHYA.RTM. Solar R333A 4) glass plate of 20 by 30 cm. Lamination
was done at 157.degree. C. during 12 minutes.
Samples were aged in a climate chamber at 85.degree. C. and 85%
relative humidity.
It was visually assessed that the sample showed clear delamination
during 3000 hours of ageing. Flash testing did not show any
significant decrease of the power output after 3000 hours of
ageing.
EXAMPLE 8
The same compounds produced in example 7 were co-extruded into film
having a total thickness of 600 micrometers and consisting of a 400
micrometer layer of the first compound and a 200 micrometer layer
of the second compound. The extrusion die was set at a temperature
of 270.degree. C.
A laminate was made by making the following stack: 1) above
co-extruded film, 2) one standard multi-crystalline solar cell 3)
APOLHYA.RTM. Solar R333A 4) glass plate of 20 by 30 cm. Lamination
was done at 157.degree. C. during 12 minutes.
Samples were aged in a climate chamber at 85.degree. C. and 85%
relative humidity.
It was visually assessed that the sample showed no delamination
during 3000 hours of ageing. Flash testing did not show any
significant decrease of the power output after 3000 hours of
ageing.
* * * * *